A typical injection molded closure of the “flip-top” type has a closure body hingedly connected to a cap. The cap is swingable about the hinged connection over the closure body. The cap and closure body are provided with mutual inter-locking means such as a protrusion which engages a lip to secure the cap to the closure body in a closed configuration. The cap and closure body are generally molded simultaneously in an open configuration with the cap adjacent the closure body.
In-mold closing devices are used for molding such closures. In order to provide a good seal and fit between the protrusion and the cap and the lip and the closure body, it is desirable to engage the respective sides of these components immediately after molding for optimizing shrinkage during cooling. The closing of the cap also simplifies handling after molding and part ejection, as this alleviates concern that the parts will interlock with each other, or damage the hinge. As well, by flexing the hinge while it is still warm, the hinge has a tendency to withstand more open and close cycles of the cap.
A device for effecting closure of a cap over a closure body is described in U.S. Pat. No. 4,351,630 (Hayberg et al) which discloses the use of a push pin mounted within one of the mold halves to push a cap into an upright position in order for a slide finger having a roller to roll over and snap shut the cap in its closed configuration. This apparatus requires synchronized movement between the pin and the slide finger which is problematic as the components have independent actuation. Accordingly, there remains the possibility of collision between the two components. Furthermore, the pin is problematic in mold design, as the pin and a piston assembly behind the pin which actuates the pin need to be directly located behind the cap. This restriction may reduce the cooling accessible to the cap and as well complicates mold design.
U.S. Pat. No. 4,741,088 (Ramella) teaches forming a cap over a closing mechanism. Closing is effected by having the mechanism move away from and then along the closure.
U.S. Pat. Nos. 4,812,116 and 4,783,056 (both of which issued to Abrams) teach the use of a flipper arm mounted to a mold cavity plate to flip a lid over a vial. As with the Hayberg and Ramella structures, Abrams has an in-mold component and accordingly doesn't avoid the problems associated with accommodating a closing unit as part of a mold.
An object of the present invention is to eliminate having a synchronized pin and slide finger arrangement to avoid the possibility of in-mold collisions. A further object of the present invention is to provide a closing device for closing a cap over an injection molded closure body without requiring an in-mold component for initial lifting of the cap.